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	<div id="winchm_template_button"><A href="breakpoint_syntax.htm" title="Previous topic"><img id="winchm_template_prev" alt="Previous topic" src="../template2/btn_prev_n.gif" border="0"></a><A href="processor_breakpoints___ba_breakpoints_.htm" title="Next topic"><img id="winchm_template_next" alt="Next topic" src="../template2/btn_next_n.gif" border="0"></a></div>
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<A href="introduction6.htm">Debugging Tools for Windows (WinDbg, KD, CDB, NTSD)</A> &gt; <A href="debugging_techniques.htm">Debugging Techniques</A> &gt; <A href="standard_debugging_techniques.htm">Standard Debugging Techniques</A> &gt; <A href="using_breakpoints.htm">Using Breakpoints</A> &gt; </div>
	<div id="winchm_template_title">Unresolved Breakpoints  (bu Breakpoints)</div>
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	<div id="winchm_template_content"><div id="mainSection"><p>If a <a href="#Bookmark1350">breakpoint</a> is set for a routine name that has not been loaded, the breakpoint is called a <i>deferred</i>, <i>virtual</i>, or <i>unresolved</i> breakpoint. (These terms are used interchangeably.) Unresolved breakpoints are not associated with any specific load of a module. Every time that a new application is loaded, it is checked for this routine name. If this routine appears, the debugger computes the actual coded address of the virtual breakpoint and enables the breakpoint.</p>
<p>If you set a breakpoint by using the <b>bu</b> command, the breakpoint is automatically considered unresolved. If this breakpoint is in a loaded module, the breakpoint is still enabled and functions normally. However, if the module is later unloaded and reloaded, this breakpoint does not vanish. On the other hand, a breakpoint that you set with <b>bp</b> is immediately resolved to an address.</p>
<p>There are three primary differences between <b>bp</b> breakpoints and <b>bu</b> breakpoints:</p>
<ul>
<li>
<p>A <b>bp</b> breakpoint location is always converted to an address. If a module change moves the code at which a <b>bp</b> breakpoint was set, the breakpoint remains at the same address. On the other hand, a <b>bu</b> breakpoint remains associated with the symbolic value (typically a symbol plus an offset) that was used, and it tracks this symbolic location even if its address changes.</p>
</li>
<li>
<p>If a <b>bp</b> breakpoint address is found in a loaded module, and if that module is later unloaded, the breakpoint is removed from the breakpoint list.  On the other hand, <b>bu</b> breakpoints persist after repeated unloads and loads. </p>
</li>
<li>
<p>Breakpoints that you set with <b>bp</b> are not saved in WinDbg <a href="#Bookmark1291">workspaces</a>. Breakpoints that are set with <b>bu</b> are saved in workspaces. </p>
</li>
</ul>
<h3><a id="controlling_address_breakpoints_and_unresolved_breakpoints"></a><a id="CONTROLLING_ADDRESS_BREAKPOINTS_AND_UNRESOLVED_BREAKPOINTS"></a>Controlling Address Breakpoints and Unresolved Breakpoints</h3>
<p>Address breakpoints can be created with the <a href="#Bookmark1980"><b>bp (Set Breakpoint)</b></a> command, or the <b>bm (Set Symbol Breakpoint)</b> command when the <b>/d</b> switch is included. Unresolved breakpoints can be created with the <b>bu (Set Unresolved Breakpoint)</b> command, or the <b>bm</b> command when the <b>/d</b> switch is not included.  Commands that disable, enable, and modify breakpoints apply to all kinds of breakpoints.  Commands that display a list of breakpoints include all breakpoints, and indicate the type of each. For a listing of these commands, see <a href="#Bookmark1351">Methods of Controlling Breakpoints</a>.</p>
<p>The WinDbg <b>Breakpoints</b> dialog box displays all breakpoints, indicating unresolved breakpoints with the notation "u". This dialog box can be used to modify any breakpoint.The <b>Command</b> text box on this dialog box can be used to create any type of breakpoint; if the type is omitted, an unresolved breakpoint is created. For details, see <a href="#Bookmark2887">Edit | Breakpoints</a>. When you set a breakpoint by using the mouse in the WinDbg <a href="#Bookmark1227">Disassembly window</a> or <a href="#Bookmark1228">Source window</a>, the debugger creates an unresolved breakpoint.</p></div></div>	
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